JPS63111697A - Wiring board and manufacture of the same - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a wiring board and a method for manufacturing the same, and particularly to a multilayer wiring board for hybrid IC and a method for manufacturing the same.

(Conventional technology) In recent years, with the increasing demand for electronic devices to be smaller and lighter, more multifunctional, faster, and more reliable, IC chips, resistors, and capacitors are being mounted on multilayer wiring boards made of ceramics such as alumina. Hybrid ICs, which have a structure in which a large number of chip components are mounted and the whole is hermetically sealed with a metal cap, are being widely used.

The ceramic multilayer wiring board used in this hybrid IC is usually manufactured by a green sheet method, a thick film method, a thick film/thin film hybrid method, or the like.

However, in such a ceramic multilayer wiring board, the insulating layer is made of ceramic (ε=8 to 10) or crystallized glass (ε-9 to 20), which has a relatively large dielectric constant (ε). Because of this, it is not possible to keep the stray capacitance of the wiring low, which hinders the high-speed operation of the mounted elements.

In order to deal with such problems, copper-polyimide multilayer wiring boards have recently been developed as wiring boards for mounting high-speed devices. As shown in FIG. 4, this wiring board has a structure in which a thin film conductor pattern 2 with a thickness of approximately 1 μm to 10 μm and a polyimide layer 3 are laminated on a ceramic substrate 1, and is manufactured as follows. ing.

That is, a thin film of two or three types of conductors with copper as the main conductor is deposited on a ceramic substrate 1 by vapor deposition or sputtering.
The first step is to form a thin film conductor pattern 2 by etching unnecessary parts using a method such as photolithography. After drying the polyimide resin on a spin coat 1, the upper and lower conductor patterns 2 are formed by photolithography. It is manufactured by repeating the second step of forming a through hole 4 for electrical connection between the two.

In the copper-polyimide multilayer wiring board manufactured by such a thin film method, the dielectric constant of the polyimide resin constituting the insulating layer is extremely low (ε-3 to 4), and the electrical resistance is lower than that of other metals. Since the conductor pattern 2 is formed of small copper, it has the advantage that the mounted elements can be operated at high speed.

(Problem to be Solved by the Invention) However, in such wiring boards, since the polyimide resin has hygroscopic properties, an IC chip, etc. is mounted on it and hermetically sealed with a metal cap, etc. to create a hybrid IC. When manufacturing a metal cap, moisture enters the mounting area inside the metal cap from the thickness direction of the polyimide layer 3.

This moisture causes problems such as short circuits in multilayer wiring due to migration, corrosion of ICs and wires, and short circuits due to condensation during temperature cycle tests.

The present invention has been made to solve these problems, and is intended for use in hybrid ICs that have improved moisture resistance, prevent moisture from entering hermetically sealed areas, and are highly reliable and capable of high-speed operation. The purpose of the present invention is to provide a multilayer wiring board and a method for manufacturing the same.

[Summary of the Invention (Means for Solving Problems) The wiring board of the present invention includes a ceramic substrate and a low dielectric constant insulating material disposed at the center of a predetermined surface of the ceramic substrate as an insulating layer. a multilayer wiring section having a Cu-based conductor pattern in multiple layers; an input/output pad formed at a peripheral portion of a predetermined surface of the ceramic substrate at a distance from the multilayer wiring section; and the input/output pad and the multilayer wiring section. and a conductive wiring pattern which is electrically connected at one end to an input/output pad and at the other end to a terminal of the multilayer wiring section, and a conductive wiring pattern which covers at least a part of the conductive wiring pattern and which is electrically connected to the multilayer wiring pattern. an insulating layer made of a moisture-resistant material formed in a ring shape on a predetermined surface of the ceramic substrate so as to surround the wiring portion;
It is characterized by comprising an annular conductor layer formed on the insulator layer, and a conductive cap having a base attached to the annular conductor layer so as to cover the multilayer wiring section.

The manufacturing method also includes a step of forming a conductive wiring pattern on a predetermined surface of a ceramic substrate with one end toward the periphery and the other end toward the center using a thick film method; and a step of forming an annular insulator layer made of crystallized glass so as to surround a central portion of a predetermined surface of the ceramic substrate, and a step of forming an annular conductor layer on the insulator layer by a thick film method. A multilayer wiring section having a polyimide resin insulating layer at the center of a predetermined surface of the ceramic substrate, and a Cu-based conductor pattern in multiple layers with a terminal connected to the other end of the conductor wiring pattern, and the uppermost layer of this multilayer wiring section. forming an input/output pad electrically connected to at least one end of the conductor wiring pattern by a thin film method at the same time as the Cu-based conductor pattern; It is characterized by consisting of a step of attaching it to the conductor layer.
9 = I am doing it.

(Function) In the wiring board and the manufacturing method thereof of the present invention, the conductive wiring pattern and the annular conductor layer for electrical connection with the internal wiring are formed by a thick film method, and the conductive wiring pattern and the annular conductor layer are formed inside the annular conductor layer. A multilayer wiring section is provided on a ceramic substrate using a thin film method using a low dielectric constant insulating material as an insulating layer and having Cu-based conductor patterns in multiple layers.

Therefore, by mounting elements such as IC chips on a multilayer wiring element, a hybrid IC capable of high-speed operation can be obtained.

In addition, by attaching a metal cap to the annular conductor layer, the multilayer wiring section is hermetically sealed and does not come into direct contact with the outside air. Since it is made of crystallized glass and moisture does not penetrate through it in the thickness direction, short-circuit corrosion accidents and the like do not occur, and a highly reliable hybrid IC can be obtained.

= 10- Furthermore, C was applied onto the exposed portion of the conductive wiring pattern using the thin film method.
Since U-type input/output pads are formed, it is easy to fix input/output leads, etc. thereon.

Further, in a wiring board in which an annular conductor layer serving as a seal ring pattern is printed and formed using a thick film conductor paste with particularly good solder wettability, it is easy to weld the metal cap with solder.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 and FIG. 2 are a perspective view and an enlarged sectional view of essential parts, respectively, showing an embodiment of the wiring board of the present invention.

In these figures, reference numeral 5 indicates a substrate made of ceramic such as alumina, and on the peripheral portion of the surface of this ceramic substrate 5, a plurality of relatively short conductor patterns 6 are provided, each extending toward the center of the substrate. They are each formed by the thick film method shown below.

That is, these short thick film conductor patterns 6 are made of, for example, CU base, Ag-Pt paste, or Au-Pt paste. A thick film conductor paste, such as Ag-Pd paste, which has good wettability with S u -Pb-based solder and has a slow diffusion rate with this solder, is screen printed to a thickness of 5 to 20 μm, and then dried. , is formed by firing.

Further, on the short thick film conductor pattern 6 formed in this way, a ring-shaped insulating layer 7 is printed with crystallized color paste and has a width such that both ends thereof are exposed and only the central part is covered. It is formed by drying and firing. Furthermore, on this ring-shaped insulator layer 7,
A ring-shaped conductor pattern 8 having a similar shape and somewhat narrower than this is formed by printing, drying, and baking the thick film conductor paste described above.

Further, on the surface of the ceramic substrate 5 inside such a ring-shaped thick film conductor pattern 8, there is a 2-layer conductor made of copper as a main conductor.
A polyimide layer 1 having approximately the same thickness as a thin film conductor pattern 9 having a thickness of approximately 1 μm to 10 μm and consisting of three types of conductors.
A copper-polyimide multilayer wiring section 11 is provided, which is formed by alternately laminating layers 0 and 0 by a thin film method as described below.

In other words, this multilayer wiring part 11 is first formed by depositing two or three types of conductors with copper as the main conductor, such as Cr/Cu and Ti/Cu, on the ceramic substrate 5 inside the ring-shaped conductor pattern 8.
, Cr/Cu/Cr, Ti/Cu/Cr, Cr/Cu/
After forming a thin film by vapor depositing or sputtering a conductor such as Au, Ti/Cu/Au, etc., a first layer thin film conductor pattern 9 is formed by etching unnecessary portions by photolithography. In this first layer thin film conductor pattern 9, the end portion 1
2 are formed so as to overlap on the entire inner end of the short thick film conductor pattern 6, and the short thick film conductor pattern 6 and the conductor pattern of the multilayer wiring section 11 are configured to be electrically connected.

On the thus formed thin film conductor pattern 9, a polyimide resin, which is an organic material, is spin-coated and dried and hardened to form a polyimide layer 10. After that, the conductor pattern 9 is etched by photolithography. Through hole 1 for electrically connecting between
form 3.

These steps are repeated to alternately stack a predetermined number of thin film conductor patterns 9 and polyimide layers 10, and finally, the uppermost layer thin film conductor pattern 9 is formed as shown below.

That is, in the uppermost layer, two or three types of conductors using the previous recording as a main conductor are deposited or sputtered on the entire surface of the substrate, and then this thin film conductor is etched.
A plurality of die pads 14 for mounting active elements such as IC chips and passive elements such as resistors and capacitors inside the ring-shaped thick film conductor pattern 8 and the mounted active elements via bonding wires. A plurality of outer lead bonding pads (OLB) 15 are formed for electrically connecting the conductor pattern of the multilayer wiring section 11 to A plurality of large-sized input/output conductor pads 16 are respectively formed.

On the wiring board of the embodiment configured as described above, elements are normally mounted in the following manner to form a hybrid IC.

That is, as shown in FIG. 3, on the tie pad 14 of the multilayer wiring section 11, an IC chip 17, a resistor, etc. (not shown) are bonded with an adhesive such as a conductive epoxy 18, and these A bonding wire 19 such as Au wire + AI wire is connected between the IC chip 17 and the OLB 15.
electrically connected by. The second part of the ring-shaped thick film conductor pattern 8 is made of Kovar or Fe/N.
The cap 20 is made of a metal such as i42 alloy, which has a coefficient of thermal expansion almost equal to that of ceramic, and has a S n / P
It is fixed with a eutectic solder 21 such as b 63 /37 alloy, and the area where the IC chip 17 and the like are mounted is hermetically sealed with an inert gas 22 such as helium or nitrogen.

Further, input/output leads such as clip leads and input/output pins (not shown) are fixed to the thin film input/output conductor pads 16'' using eutectic solder or the like.

Therefore, in the hybrid IC configured in this manner using the wiring board of the embodiment, the insulator layer of the multilayer wiring section 11 on which the IC chip 17 and the like are mounted has a dielectric property compared to ceramic or crystallized glass. Since it is made of polyimide resin with a low polyimide resin, the stray capacitance of the wiring can be reduced, and the operation speed can be increased.

Further, the area where the IC chip 17 and the like are mounted is hermetically sealed with a metal cap 20, and the insulating layer around the substrate exposed outside the metal cap 20 is made of moisture-resistant material. Since it is made of high-quality ceramic such as alumina and crystallized glass, moisture is completely prevented from entering the mounting area inside the metal cap 20, and there is no occurrence of migration, wire corrosion, dew condensation, etc. Furthermore, a ring-shaped conductor pattern 8 that becomes a seal ring pattern
is formed as a thick film of a conductor that has good wettability with solder, and on the exposed part of the short thick film conductor pattern 6, a thin film is formed of two or three types of conductors with copper as the main conductor, which has good solderability. Since the input/output conductor pads 1-6 are formed, a hybrid IC with high fixing strength for the metal cap 20, input/output leads, etc. can be obtained.

[Effects of the Invention] As is clear from the above description, according to the wiring board and the method for manufacturing the same of the present invention, moisture does not infiltrate into the mounting area of the element that is hermetically sealed with a metal cap or the like. Therefore, short circuit corrosion accidents will not occur. Therefore, it is possible to obtain a hybrid IC that has high reliability and allows high-speed operation of its elements.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a perspective view and an enlarged cross-sectional view of the main parts of an embodiment of the wiring board of the present invention, respectively, and FIG. 3 is an enlarged view of the main parts of a hybrid IC constructed using the wiring board of the embodiment. 4 is a cross-sectional view of a conventional copper-polyimide multilayer wiring board. 5...Ceramic substrate 6...Short thick film conductor pattern 7...
・・・・・・Ring-shaped insulator layer 8 ・・・・・・・・・
Ring-shaped thick film conductor pattern 9...Thin film conductor pattern 10...Polyimide layer 11...Multilayer wiring section 13... ...Through hole 14...Gui pad 15...0LB 17...IC chip 20...・Metal cap 21...
・・・Solder

Claims (13)

[Claims] (1) a ceramic substrate; a multilayer wiring section having a multilayered Cu-based conductor pattern with a low dielectric constant insulating material as an insulator layer disposed at the center of a predetermined surface of the ceramic substrate; An input/output pad is formed on the periphery to be spaced apart from the multilayer wiring section, and an input/output pad is provided between the input/output pad and the multilayer wiring section, one end of which is an input/output pad, and the other end of which is an input/output pad of the multilayer wiring section. conductive wiring patterns each electrically connected to the terminals; and a moisture-proof ring formed in a ring shape on a predetermined surface of the ceramic substrate so as to cover at least a portion of each of the conductive wiring patterns and to surround the multilayer wiring section. an insulator layer made of a conductive material; an annular conductor layer formed on the insulator layer; a conductive cap having a base attached to the annular conductor layer so as to cover the multilayer wiring section; A wiring board comprising: (2) The wiring board according to claim 1, wherein the ceramic substrate is a substrate made of alumina. (3) Cu-based conductor pattern is Cr/Cu, Ti/Cu
, Cr/Cu/Cr, Ti/Cu/Ti, Cr/Cu/
The wiring board according to claim 1, which is made of Au or Ti/Cu/Au. (4) The end of the lowest layer of the Cu-based conductor pattern of the Cu-based conductor pattern constituting the multilayer wiring section is overlapped and electrically connected to the other end of the conductive wiring pattern. Wiring board described in section. (5) The wiring board according to claim 1, wherein the low dielectric constant insulating material is a polyimide resin. (6) The wiring board according to claim 1, wherein the moisture-resistant material is crystallized glass. (7) The wiring board according to claim 1, wherein the conductive cap is a metal cap. (8) The wiring board according to claim 1, wherein the annular conductive layer is a seal ring pattern for attaching a conductive cap. (9) forming a conductive wiring pattern on a predetermined surface of a ceramic substrate with one end facing the periphery and the other end facing the center using a thick film method; forming an annular insulating layer made of crystallized glass so as to surround a central portion of a predetermined surface of the substrate; forming an annular conductive layer on the insulating layer by a thick film method; A multilayer wiring section having a polyimide resin as an insulating layer in the center of a predetermined surface and a Cu-based conductor pattern in multiple layers with terminals connected to the other end of the conductor wiring pattern, and a Cu-based conductor in the uppermost layer of this multilayer wiring section. simultaneously forming an input/output pad electrically connected to at least one end of the conductor wiring pattern by a thin film method; and attaching a base of a conductive cap to the annular conductor layer so as to cover the multilayer wiring part. A method for manufacturing a wiring board, comprising the steps of: attaching the board. (10) The process of forming the conductor wiring pattern and the annular conductor layer is performed by printing, drying, and baking a thick film conductor paste that has good solder wettability and a slow diffusion rate with solder. A method for manufacturing a wiring board according to scope item 9. (11) The method of manufacturing a wiring board according to claim 9, wherein the step of forming the insulator layer is performed by printing, drying, and firing a thick film crystallized glass paste. (12) The step of forming a Cu-based conductor pattern involves Cr/
Cu, Ti/Cu, Cr/Cu/Cr, Ti/Cu/T
The method for manufacturing a wiring board according to claim 9, wherein a thin film made of i, Cr/Cu/Au, or Ti/Cu/Au is deposited or sputtered, and unnecessary parts are etched by photolithography. . (13) The step of forming an insulating layer of polyimide resin is as follows:
10. The method of manufacturing a wiring board according to claim 9, wherein a thin film of polyimide resin is formed by spin coating and etched by photolithography.